Disclosures: Carmen M. Cirstea, MD, PhD: Nothing to disclose

Objective: Despite major advances in acute stoke management, most patients still carry different degrees of arm motor impairment when they enter the subacute epoch. This phase corresponds to an initiation of brain repair, being characterized by robust biological events, e.g., intracortical excitability changes. Such changes strongly support recovery, either spontaneously or with the support of rehabilitation. Understanding the nature and evolution of these events could be key to optimizing clinical care. Unfortunately, such studies in humans are lacking. We used MR spectroscopy to non-invasively study the intracortical excitability of motor/premotor cortices (neural substrates supporting arm function and targets of great interest for noninvasive brain stimulation) in subacute and chronic survivors. We also investigated whether these changes are adaptive, maladaptive, or functionally irrelevant.

Design: Longitudinal prospective study

Setting: Neuroimaging

Participants: Thirty-two subcortical stroke survivors within three (subacute, n=6) and after six (chronic, n=26) months post-diagnosis; 19 age/sex-matched healthy controls.

Interventions: N/A

Main Outcome Measures: MR spectroscopy-measured intracortical excitability (composite measure of glutamate and glutamine, Glx) of arm representation area in motor/premotor cortices; Arm impairment measure (Fugl-Meyer test).

Results: Relative to controls, the subacute survivors exhibited lower levels of Glx in both hemispheres (by -21.2% to -29.2%, P<.02 for all) while the chronic displayed normal levels (0.2

Conclusions: These data provide evidence for reduced bilateral intracortical excitability in subacute stroke. Additional work is underway to decipher the functional implications of such change. The increase in Glx with increasing time post-stroke implies that intracortical excitability changes in favor of increases excitability with recovery. The relationship between intact hemisphere excitability and clinical severity may be suggestive of an adaptive role in more severely impaired patients. This understanding is paramount to develop new or modify current treatments to better target neural events to enhance recovery after stroke.

Level of Evidence: Level I

« Back to AAPM&R Annual Assembly 2019

PM&R Meeting Abstracts - https://pmrjabstracts.org/abstract/intracortical-excitability-after-stroke-a-mr-spectroscopy-study/